Recently we met with David Lyus at GEW and we talked about the changes taking place within the marketplace - the fact is that new technologies are being innovated and adopted resulting in the traditional ways of doing things being challenged and in constant review. Hybrid technologies are growing as they deploy the advantages of two different processes.

With this in mind, GEW's ArcLED technology powered with their uniquely innovative RHINO hybrid power supply means they could be onto a winner.

So David, please explain about both arc and LED...

"These are the options that digital printing machinery manufacturers have at their disposal for curing ink. The issue is that a lot of people are speculating about when arc lamps will give up and LED will take over. At GEW however, we see the two technologies as complimentary rather than competitive."

What is the difference in reality?

"The most common way of generating UV light in our industry is still with a medium pressure mercury arc lamp. LEDs’ use is increasing as they offer energy saving opportunities, have a more controllable output and radiate less heat onto the substrate. However, arc lamps are still the preferred curing method for single pass inkjet as they too offer their own advantages. The available ink sets are well proven as the technology is more mature than LED and therefore more widely available, ink is lower in cost and as a result it poses less of a perceived business risk. At GEW we see the benefits and the challenges of both technologies and believe that in an ideal world one would be able to seamlessly use both depending on the specific job. And this very goal is the essence of our new ArcLED technology."

As LED is the newer technology, what are its advantages?

"LEDs are instantly switchable so when the UV source is not needed the LED array is simply turned off and consumes no power, whilst a mercury arc lamp switches to standby mode and still consumes around 25 W/cm. On machines with frequent job change-overs or where the lamps’ duty cycle is relatively low, the potential for energy savings is large. It may come as a surprise to some that a UV LED array’s electrical efficiency is only slightly higher than that of an arc lamp, but their high intensity output means that they can be significantly more effective in some applications. "

Why does intensity matter?

"UV intensity is critical for effective UV curing. A useful analogy is to consider driving in a nail with a hammer: the UV dose is like how many times you hit the nail, and the intensity is the weight of the hammer. It stands to reason that a heavier hammer – i.e. a higher intensity – is going to be more effective at getting the job done.

Let’s use full curing of opaque white ink as an example. With arc lamps this is a relatively slow process because the short wave, relatively low intensity output of the lamp struggles to penetrate the thick, heavily pigmented ink film. We now supply many of our customers with an LED array for this process instead, where the high intensity long wave output penetrates the ink with ease to deliver a full cure at double the production speed, using only a quarter of the power."

What are the operational advantages of LEDs?

"Typically an LED’s life is in excess of 20,000 hours operating time, whilst an arc lamp lasts for around 3,000 hours of operating time and standby time. Switching the LEDs off when not in use means that they can potentially outlast the machine to which they are fitted. However, if a replacement LED array is needed, this can easily cost more than all of the UV lamps used over the equivalent period. Nevertheless the time spent on system maintenance is greatly reduced, and there are no reflectors or shutters to clean or inspect which all helps to increase the machine’s uptime."

Is LED compatible with any type of substrate?

"LED curing is compatible with a much wider range of heat sensitive substrates than mercury lamps, which radiate a significant amount of heat besides the UV. With an LED, nearly all of the heat is absorbed by a heatsink behind the array, so the warming effect on the substrate is much less. Remember though that the UV curing reaction is exothermic, so there will always be some heating of the substrate no matter how cold the light source is."

It really seems that LED is the future, where does this leave arc lamps?

"Arc is still a popular solution. It is versatile with broad UV output meaning more flexibility for ink manufacturers and lower cost for both inks and varnishes. Varnishes cured with mercury lamps also give a superior finish to the product.

For wider curing systems, the cost increase with arc lamps is much less steep than with LEDs, and where a curing solution over a 500mm wide is needed, arc lamp systems are extremely competitive."

Since there is a place for both, what is the future for curing?

"Where multiple printing processes are used, machinery manufacturers and end users alike now have the opportunity to draw on the strengths that both curing technologies offer, and in future the most efficient, most flexible combination printing machines will run hybrid UV curing systems.

Where manufacturers offer a product range consisting of machines running either LED or mercury arc curing, they can now standardise by using the same electronic power supply and control for all machines, with the only variable being whether the UV cassette is an arc or LED type. For this reason the ArcLED hybrid UV system is proving very popular with press OEMs."

With your successful launch at Labelexpo ArcLED is clearly already being used in the label sector, what other application areas do you foresee?

"For decorative printing we can see this being very popular in different application. The ink companies love the concept and technology and I think as our presence at InPrint will demonstrate, the decorative marketplace will see an increase in the use of these technologies for sure."

ARCLED Product Features:

The most effective hybrid UV system in the marketHigh LED power density up to 22 W/cm2E2C arc lamp technology is the most energy efficient availableUniform UV output and wavelength RHINO ArcLED power supply detects lamp type and delivers correct power automatically Common interface for both technologiesLowest energy consumption - most efficient in its class Proactive downtime avoidance with GEW embedded service5-year warranty